Brain Damage in a New Hemorrhagic Shock Model in the Rat Using Long-Term Recovery

A new shock model in the rat using hemorrhagic hypotension for production of brain damage is described. Hemorrhagic shock was induced by lowering arterial blood pressure with bleeding. The MABP was maintained at approximately 25 mm Hg, accompanied by isoelectric EEG, and then shed blood was retransfused. At 1 week of recovery, morphological and 45Ca autoradiographic changes were examined. No brain damage was observed in rats after 1 min of isoelectric EEG. Mild neuronal damage in the hippocampal CA1 subfield was seen in some animals after 2 min of isoelectric EEG. Severe and consistent neuronal loss in the hippocampal CA1 subfield was recognized after 3 min of isoelectric EEG. Additional damage was also seen in the dentate hilus and the thalamus in some animals. This model can be used to study the pathophysiology of postshock brain damage and to assess new therapies following shock.